Corn heads are used with a combine base unit to permit the harvesting of corn. Corn heads include a frame and a toolbar extending across the width of the frame to which row units and optional chopping units are attached. Each row unit includes two adjacent stalk rolls mounted for rotation on adjacent rotating shafts extending from a row unit gearcase. The stalk rolls are long and slender, cantilevered forward and generally horizontal from the row unit gearcase on which they are mounted. The two stalk rolls define a gap therebetween into which corn stalks are inserted during operation. Each of the stalk rolls are fixed to a respective rotating shaft that extends from the front of a row unit gearcase.
One current technique for fixing a stalk roll to a corn head gearcase output shaft employs two bolts and two nuts as well as a set of double roll pins to fix the axial location of the stalk roll on the shaft. Another known technique employs a long bolt having a conic (frustoconical) contact surface engaging a conic stalk roll seat at one end of the stalk roll and a conic surface on the output shaft engaging a conic surface toward the other stalk roll end. The axis of conic engagement at one end is rarely perfectly coaxial with the axis of conic engagement near the other end. As the bolt is tightened, a bending moment is introduced. If the shaft stiffness prevents bending, one or both of the contact surfaces will have point contact, not full conic surface compliance, thus having an increased tendency to loosen or fail.
The gearcase output shafts drive the stalk rolls in a direction that pulls the corn stalks downward between the two rolls and pulls off the ears of corn on the stalks. As the stalk rolls rotate and pinch the corn stalks therebetween, they experience fluctuating loads in a direction perpendicular to the longitudinal extent of the rolls and shafts. These fluctuating loads can loosen the threaded fasteners that secure the stalk rolls to their rotating shafts. What is needed is a stalk roll that does not loosen as easily. What is also needed is a stalk roll that can be easily removed while still providing this better attachment.
What is also needed is a stalk roll that can be held in closer concentric alignment to the shaft on which it is supported in order to maintain a constant spacing between itself and the adjacent stalk roll shaft.